Fusible plug device



T. w.,Lowr- 1,779,098

FUSIBLE PLUG DEVICE Filed Oct. 3, 1928 2 Sheets-Sheet 1 Oct. 21, 1930.

. 5 0 m 2 fi Y QN H 8/ ,K we N. a w m 4 \wx W. m mo f 8 r T 7 MI I J HI Patented Oct. 21,'1930 (THOMAS wIL rAM-rowE,'- or wmnirne, MANITOBAQCANADAQ I; Q FUsrBLE Prue DEViCE Y "n ip'l'iceti qn fnlea omb; 13("1928. SeriaiiNo:eiigis' My "invention relates to certain new and useful mprovements in devices to protect v Y boilers against damage due to l w Water and to prevent tviolent explosions which fre- 5 quentlyoccur Whenfa boiler-is operated with" fused metal frequent renewal of thefusible w an insuflicient supply o fwater.

Heretofore it has low water alarms of Various designs, none of which, so far as I and aware'win put wa 1 ter into the boiler,"or.quench therfire and as l a 're'sult they are not satisfactory, Another deviceis the ordinary fusibleplug'whi'ch has vnotsatisfactorilyf supplied what. the me chanicsof the United States and Canada lie-.7 15 quire therefore, these fusible plugs have not 1 been made compulsory forf use by law nor have they been exclusively Voluntarily used. The reasons for this arefthatzthe precipitation of Scale "and foreign matter, in the e terflduring service adheres to the end of the "plug-Where it projects into thewater in .the

boiler. The scale then resists the boiler pres; sure to force the steam and water to escape, even thoughthe iusible metal has melted out of the plug, thus rendering the device inoperative for its intended purpose, Again, frequent occurrences have been noted when the fusible meta-l had melted out of the plug for some time and "the"scale'which had water and consequent melting out of the I metalwas advocated" ,Without goodresults.

invention therefore primarily has for.

its object to provide a fusible plug vdevice free from the aforesaidobjections;the fusible plugof which will fusealnd quench the fire automatically, only when water falls below 7 the highest partcof; the boiler or firebox, that 1 is subjectto the productsrofcombustionj.

- Inits generic nature the: invention includes means to exclude absolutely the formationlof scale over the fusible ineta-l by'pro viding a chamber "for the circulation of disi tilled water and steam in order'to protect the been the practice use being had plied; to a fusiblephighgainst being incontact with the lm-pure water which maybe'in the boil r;

"More specifically," theinvention provides a means Wherebythe device automatically provides its own purewater byqdistillation' (condensation) so as tomaintain pure water and steamin the device; thereby prve'nti'rigQ blocking; the foutl'et with accumulations of sediment and scale and -"also Tayoi din g the" necessity, of renewing the fusible" nieta'hun less the boiler'has be'comeshort ofnwater'.

Other obj ectswill in part be obvious part'be pointed outhle'reing't'fter,f i I i ,To the attainment of the aforesaid objects and ends .the' invention includes these novel features ofconstruction; combination {and er;

rangement of parts"which:will hei einafter be 7 fully f'de'scri'bed and w en be specifically. pointed out in the appended, 1aim reergn l a co yi d awin i which Figurefl is tudinal section" showing my invention up;

boileli w A y e 4 I Figure v is'a crosssection on'the 'line' 2''2 of Figurel? lV J 'F 'gure- 1s an enlargedyerticalsection of the mveritmn, a fragment'ofla crown sheet being shown a 'freg menteryiyertica1 longi-Q Figure5 is a top'endlyie voffthe deiiie; 1 l

"Figure 6fis a bottom @nd v 1 f the e i vice} I v.

Figure 7 is (a cross'section on the '1ine77h OfFigureB. :1 i

H FigurefSfis I of a returnpipe'boiler Withmy inizentionin modifieduforma pplied;

nal sei ctijon'of' the deyice'shown in Figure 8 Figure 10 is a section of 'another modific'a tion of myj nventionfi In the drawlng's, n Whichflike numerals of reference indicate like parts in all of the figures,.1 represents'the boiler having the I usual firebox 2,'Water space3 andfstea-mspace 4, The'boiler, of course maybe of 'anytype Gear fragmen ry section as my inventionis adaptable to useYon an'y 1 type of boiler having a steam space and a water space through which my device can be projected from the firebox.

The specific embodiment illustrated in Figures 3 to 7 inclusive, comprises an elongated body 6 preferably of cylindrical form, and haiin adjacent its lower end an external thread 7 preferably tapered so as to screw into the crown sheet or head sheet 5 of the boiler,

The lower end of the body has an angled portion (square, hexagon or other similar form) 8 on which a wrench may be placed for the purpose of screwing the device into the crown sheet. The portion 8 will hereinafter be referred to as the nut portion.

Extending inwardly from the upper end of the body 6 is a pair of ducts or passages 9-9 that communicate with a chamber portion 10 located adjacent to the crown sheet end of the device, the chamber portion 10 merging with the outlet duct or passage 11 that opens through the lower end of the body 6 as shown. This passage 11 is normally closed, however, by a fusible plug 12 of the usual material employed in fusible plug devices, or any other suitable material for the purpose.

Where the device is to be used on return tubular boilers (see Figures 8 and 9) the tubular body 6 is laterally bent adjacent its lower end as at 13 so that the outlet passage 11 may lie horizontally instead of vertically and enable the device to be screwed into a vertical wall instead of into a horizontal wall of the boiler. Where difiiculty may be encountered in placing the devices because of the position of the tubes the modification illustrated in Figure 10 may be employed and by reference to this figure it will be seen that the elongated body 6 is provided with a flange 14 to fit against the shoulder 15 of the outer part 7 of the two-part plug so that the elongated body 6 may have a swivel connection with the plug portion 7 it being secured against swivelling after placement by a jam plug 17 threaded into the plug part 7*, the plug part 17 having the nut portion 8* and carrying the fusible material 12". The cham-- ber 10* and ducts 9* are provided, above, and correspond in purpose and function to the chambers 10 and 9 respectively in the preceding embodiments of the invention, the vertical wall of the boiler into which the device is secured being designated by 5* It will be observed from the foregoing that in all applications of my invention the upper end of the elongated body lies above the water line or water space of the boiler and at all times in communication with the steam space so that the passages 9 and chamber 10 may be filled with steam and water when the boiler is carrying steam and with pure water of condensation when the boiler shuts down. Thus at no time does the dirty water of the boiler get into the chamber 10 and/ or ducts 9*.

Further it will be seen that as soon as the boiler which has been shut down starts up again the condensed water within the chamber 10 will take on the temperature of the outside water within the water space and boiler, thus generating steam and assist in keeping the passages 9 free from any possible obstruction.

As will be seen, the primary novel feature of this invention is that it automatically ensures the manufacture of its own pure water by distillation) and this pure water and steam are used to prevent scale formation that would tend to obstruct the passages and thus avoid the necessity of renewing the fusible metal unless the boiler has become short of water and the metal has fused in consequence thereof.

A further novel feature of the invention is that the fusible metal is not only in contact with the impinging gases of the products of combustion at one end, but its opposite end is not in contact with the impure water of the boiler, such as obtains with other devices of this general hind. Again the pure water and steam circulating chamber of my invention not only excludes the impure water of the boiler from the water end of the fusible metal but in doing so provides a better circulating method for the protection of the fusible metal when in service.

When water becomes low in a boiler and the plates and other parts of l-J exposed to the products of combustion they gradually and quickly increase in temperature above that of the steam and water then in the boiler until they become so ductile as to yield to pressure in the boiler and destruction of the boiler follows.

i ith my invention the fusible metal arranged to melt at a temperature lower than the danger point of separation, and suiiicient ly low to prevent injury to the boiler or loss of life due to its destruction.

From the foregoing description, taken in connection with the accompanying crawings, it thought the construction, operation and advantages of my invention will be'clear to those skilled in the and further I desire it understood that slight changes in the details of construction, combination and arrangemei'it of parts may be made without departing front the spirit of the invention or the scope of the appended claims.

What I claim is:

1. In boilers, a fusible plug device comprising a fitting including a body in part located in the steam space of the boiler and having a water and steam chamber, and in part located in the firebox of the boiler, and a fusible plug in said body, one end of which plug is in register with said chamber and the other end is engosed to the products of combustion in the firebox, that portion of the body part that is located within the steam top of :the boiler.

space of' the boiler terminating short of the 2. In boilers, a fusible-plug device comprising afitting provided with, a passage through the same closed at one end b-y-a fusible plug and having a'water and steam chamber betweenthe plug'andl'the end of the device within the steam space of the boiler to exclude the impure water, of the boiler from the plugged passage and fusible plug, said fusible plug device-being wholly located within the boiler.

3. In boilers, a fusible plug device having a'passage closed'at one'en ing with the steam space of theboiler and the closed end communicating with the vfire- 7 tending from; one end inwardly. and having H a chamber with which said ducts communi- 7 box whereb 'the fusible plug will have one of its ends protectedby pure Water and steam and its'other end exposed to the prod ucts of combustion, said fusible 'plug device being wholly located within the boiler. v 4. A fusible lug device comprising an velongated body aving a pair of ductsextending from one end inwardly and having a chamber with which said ducts communicate, said body havingan outlet passage from said chamber through the other end of the body and a fusible plug normally closing said outlet passage. 7 y

5. A fusible plug device comprising an elongated body having a -pair of ducts ex cate, said body having an outlet passage from said chamber through the other end of the body, a fusible plug'normallyclosingv provided with means to mount it in said wall in position to hold the other end of said I body in the steam space of the boiler, a part of said'body being within the water space of the boiler, said body having a, passage through the same from end toend, that portion of said passage, which lies adjacent the -mounted end of the'body being closed by a fusible plug, said plug being exposed in part" to the productsof combustion in the firebox,

said fusible plug device being wholly located within the boiler.

7 In combination with water space and a steam space, a firebox and a wall between the firebox and the steam and" water spaces; a fusible plug device com end of the plug whereby water of condensabya fusible plug,

the open end of said passage communicatthrough the same from end to end, that porofjsaid body being'within the water space of the boiler, saidbody having a passage ,tion'of said passage which lies adjacent the mounted end of the body being closed by a I fusible plug, said plug being exposed in part I to the products of combustion in the firebox,

constituting a chamber adjacent the inner said passage also including an enlargement tion and steam will protect said plug against located within the boiler. 8. In combination with a boiler having a fusion hile theboiler is functioning, rop I 'erly, said fusible plug device being w gu 1 c I firebox and steam and water spaces separatto edf 'om thefirebox by a wall, a fusibl plug 7 V I device comprising an elongated body mountedin the wall and projectingthrough the 7 water space of, the boiler vinto the steam space, said elongatedbodyhaving a passage through the same to effect communication between, the steam space and the fireboxv at times, a fusible :plug ,normally' closing said passage, one end of said fusible plug being; in communication with the products of combustion in'thelfi rebox and the other end in communication with the steam in the'boiler,

said fusible plug device being wholly located f within the boiler, all being substantially as shownand described.

. In combination with'aboileh a fusible plugdevice comprising a fitting arranged to lie in art in the water space and in part in ithe steam spaceof a boiler and communia fusible plug in said fitting and'having one end subject to the products of combustion in the firebox, and means to protect the other end of saidrplug from dirty water in the boiler while maintaining said other end in -'cate at one end with the firebox of the'boiler,

communication with the steam space of the boiler, said fusible plug device being whollylocated within the boilerl V v 10. In combination with a boiler, a fusible lie, inpart int-he Water space and in part in the'steam space of a boiler and communicate a a a at one end with the firebox of the boiler, a

fusible plug, in, said fitting and having one 1 I end subject to the products of combustion in end of the plug,,said fusible plug device being wholly located within the boiler. '1

. p THOMAS WILLIAM LOWE-. c

a boiler having a f prising an elongated body one end of which is provided with means to mountiit in said wall in position to hold the other end of saidv body in the'steam space of the boiler, a part I the firebox, and means to'maint-ain distilledv water andsteam in contact with said other 7 t v .110 plugdevice comprising a fitting arranged to v t 

